textproduct: Rapid City

KEY MESSAGES

- Warmer today, then becoming unsettled and cooler.

- Strong to severe storms likely this afternoon and evening across western SD.

- Elevated fire weather conditions continue today across portions of northeast WY.

- Wildfire smoke is expected to linger much of the week, with thicker smoke at times across the western third

UPDATE

Issued at 440 PM MDT Tue Aug 11 2026

A Severe Thunderstorm Watch has been issued for western South Dakota that is in effect until 8PM.

A storm developed in the northern Black Hills and moved southeast. This storm was able to tap into the available moisture and heat energy and grew quite large. Hail stone reports from this storm have been upwards of 2.5 to 3.5 inches in diameter. In addition to the large hail, locally heavy rain and gusty winds have also been reported from these early afternoon storms.

Looking forward, there continues to be storm development in western and northwestern SD. These storms will track east-to- southeast through the SD plains. Strong to severe storms are still likely with large hail and strong winds being the main concerns but the tornado threat can't be completely ruled out.

Stay up on the latest weather information through the evening.

DISCUSSION

(This Afternoon Through Monday) Issued at 120 PM MDT Tue Aug 11 2026

It's another wait and watch the sky day as more strong to severe storms are looking likely. Latest hi res model guidance has thunderstorm initiation happening by 2 to 4PM near the northern Black Hills and in NW SD. As of this writing (12:30PM), clouds are starting to bubble up over the central and northern Black Hills, indications that the CAP is slowly being eroded away. Using the HRRR Convective Hazard Forecast, the time frame from 4PM to 8PM has the highest chances for severe weather in western SD, just east of the Black Hills. From there, probabilities diminish and track southeast to near zero by 10PM in southern SD.

When these storms get going, they are expected to track southeast through the western SD plains. Main concerns now are large hail, then strong winds. Isolated tornadoes can't be ruled out at this time.

Wednesday is the beginning of a big pattern change over the area. Upper level high pressure will slide southeast, allowing for moisture to flow into the area due to southwest flow. For now, expecting clouds to build and last through Friday. So a cloudy few days are in store. Thunderstorms are also likely tomorrow afternoon and evening and we can't rule out severe weather. At the surface, moist, easterly flow north of a developing surface low in eastern Colorado/western Kansas will allow for moderate to strong destabilization across parts of Nebraska/southern South Dakota. Steep mid-level lapse rates and moderate to strong effective shear will promote supercell development from near the Black Hills and south into Nebraska. Large hail and isolated severe wind gusts would be possible initially.

Continued rain and storm chances last for the rest of the week too.

AVIATION

(For the 00Z TAFS Through 00Z Wednesday Evening) Issued At 505 PM MDT Tue Aug 11 2026

Scattered strong/severe thunderstorms are expected through about 12/06z over western SD. The strongest storms will contain LIFR conditions as well as strong erratic winds and hail. A storm may come off the Black Hills and affect KRAP until about 12/01z. As the storms end, a smattering of IFR/MVFR CIGS may develop overnight into Wednesday morning. Additional showers/storms are expected Wednesday with local IFR conditions.

FIRE WEATHER

Issued At 1152 AM MDT Tue Aug 11 2026

Hot and dry weather with elevated fire weather conditions (especially over northeastern WY) will continue through today. Cooler, unsettled, and wetter weather moves into the region tomorrow and will last into the weekend.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.